The present invention relates to a method and apparatus for withdrawal of flowable particulate material from a hopper.
In the storage of particulate materials in hoppers, the problem is frequently encountered that the particulate material forms within the hopper a compacted bridge which prevents free downflow of the particulate material through the hopper body. This problem is most frequently encountered adjacent the usually converging side wall of the hopper body, immediately above the lower discharge port of the hopper; and arises through mismatching of the flowing properties and/or the angle of repose of the flowable material with the angle of convergence of the hopper walls, so that the effect of the inward sloping of the side walls of the hopper body is to cause the particulate material to be compacted together, effectively preventing discharge of the particulate material through the normal lower discharge opening.
Before the present invention, once this problem has been encountered in a storage facility, there has been no satisfactory way of obtaining an uninterrupted outflow of the material from the interior of the hopper. Re-design and reconstruction of the hopper is inappropriate if the hopper is to be used with materials of varying flowing characteristics and is in any event frequently prohibitively expensive. The use of simple hand-held implements to break-up the obstruction is effective only as a temporary expedient and will often expose operatives to hazards of injury and contamination by irritating or noxious stored materials.